CN108666338B

CN108666338B - Display device

Info

Publication number: CN108666338B
Application number: CN201710813708.2A
Authority: CN
Inventors: 胡顺源; 谢朝桦; 颜子旻; 林明昌; 刘育欣; 郭书銘; 赵明义
Original assignee: Innolux Display Corp
Current assignee: Innolux Corp
Priority date: 2017-03-31
Filing date: 2017-09-11
Publication date: 2021-12-21
Anticipated expiration: 2037-09-11
Also published as: KR102588970B1; US20240264485A1; US11474392B2; CN108695354B; US20190162992A1; US20220066247A1; CN108666338A; CN114594878B; US20230051002A1; US20180284501A1; US20200257146A1; US11619844B2; US20180284934A1; US20210286207A1; US11868001B2; US10073294B1; US12099272B2; US20230350245A1; CN108693992A; US11048117B2

Abstract

The present disclosure provides a display device including a light emitting unit including a light emitting portion, wherein a first surface of the light emitting portion has a light extraction structure, and a roughness of the light extraction structure is greater than 0.2 μm, and a substrate including a connection portion disposed on a second surface opposite to the first surface, the light emitting unit also including a protection portion surrounding the light emitting portion and the connection portion, the substrate including a bonding pad, wherein the bonding pad is electrically connected to the connection portion of the light emitting unit.

Description

Display device

Technical Field

The present disclosure relates to a display device, and more particularly, to a display device including micro light emitting diodes.

Background

With the development of digital technology, display devices have been widely used in various aspects of daily life, for example, they have been widely used in modern information devices such as televisions, notebooks, computers, mobile phones, smart phones, etc., and such display devices are continuously developing toward lightness, thinness, shortness, and fashion. And the display device comprises a light emitting diode display device.

Micro light emitting diodes (μ LEDs) use recombination (recombination) of electron-hole pairs in a p-n junction to generate electromagnetic radiation (e.g., light). Recombination of electron-hole pairs injected into the depletion region in a forward biased P-N junction formed of a direct band gap material such as GaAs or GaN generates electromagnetic radiation. The electromagnetic radiation may be in the visible or non-visible region, and materials with different energy gaps may form micro-leds of different colors.

Under the current trend of mass production in the micro-led display device industry, the reduction of the production cost of any micro-led display device can bring great economic benefits. However, the current display devices are not satisfactory in every respect.

Therefore, there is still a need for a display device that can further improve the display quality or reduce the manufacturing cost.

Disclosure of Invention

Some embodiments of the present disclosure provide a display device, which includes a light emitting unit including a light emitting portion disposed on a connection portion, wherein a first surface of the light emitting portion has a light extraction structure, and a roughness of the light extraction structure is greater than 0.2 μm. The light emitting unit also includes a protective portion surrounding the light emitting portion and the connecting portion. The display device also comprises a substrate with a bonding pad, wherein the bonding pad is electrically connected with the connecting part of the light-emitting unit.

Some embodiments of the present disclosure provide a display device including a light emitting unit including a light emitting portion having a first surface and an opposite second surface. The light emitting unit also includes a connecting portion adjacent to the second surface of the light emitting portion. The light emitting unit also includes a protection portion surrounding the light emitting portion and the connecting portion. The light emitting unit further includes a transparent structure disposed on the first surface of the light emitting portion, wherein a refractive index of the transparent structure decreases in a direction from the second surface of the light emitting portion toward the first surface. The display device also comprises a substrate with a bonding pad, wherein the substrate is provided with a plurality of active components and is electrically connected with the connecting part of the light-emitting unit through the bonding pad.

Some embodiments of the present disclosure provide a display device having a blue pixel region, a green pixel region and a red pixel region, the display device including a first light emitting unit disposed in the blue pixel region, wherein light emitted from the first light emitting unit has a first dominant wavelength, and the light emitted from the first light emitting unit is blue light. The display device also comprises a second light-emitting unit arranged in the green pixel area, wherein the light emitted by the second light-emitting unit has a second dominant wavelength. The display device further includes a third light emitting unit disposed in the red pixel region, wherein light emitted from the third light emitting unit has a third dominant wavelength, and a difference between the second dominant wavelength and the third dominant wavelength is greater than 4 nm.

Drawings

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below, wherein:

fig. 1A-1B are schematic cross-sectional views of a process of forming a bonding layer having a high melting point according to some embodiments of the present disclosure.

FIG. 1C is a graph of concentration distribution versus location of a second component within a junction layer, according to some embodiments of the present disclosure.

Fig. 2A-2B are cross-sectional schematic views of processes of forming a display device with a bonding layer having a high melting point, according to some embodiments of the present disclosure.

FIG. 2C is a graph of concentration distribution versus location of a second component within a junction layer, according to some embodiments of the present disclosure.

Fig. 3A-3B are cross-sectional schematic views of processes of forming a bonding layer with a high melting point according to some embodiments of the present disclosure.

FIG. 3C is a graph of concentration distribution versus location of a second component within a junction layer, according to some embodiments of the present disclosure.

Fig. 4 is a cross-sectional schematic view of a display device, according to some embodiments of the present disclosure.

Fig. 5 is a cross-sectional schematic view of a display device, according to some embodiments of the present disclosure.

Fig. 6 is a cross-sectional schematic view of a display device, according to some embodiments of the present disclosure.

Fig. 7 is a cross-sectional schematic view of a display device, according to some embodiments of the present disclosure.

Fig. 8 is a cross-sectional schematic view of a display device, according to some embodiments of the present disclosure.

Fig. 9 is a cross-sectional schematic view of a display device, according to some embodiments of the present disclosure.

Fig. 10 is a cross-sectional schematic view of a display device, according to some embodiments of the present disclosure.

Fig. 11 is a cross-sectional schematic view of a display device, according to some embodiments of the present disclosure.

Fig. 12 is a cross-sectional schematic view of a display device, according to some embodiments of the present disclosure.

Fig. 13 is a cross-sectional schematic view of a display device, according to some embodiments of the present disclosure.

Fig. 14 is a cross-sectional schematic view of a display device, according to some embodiments of the present disclosure.

Fig. 15 is a cross-sectional schematic view of a display device, according to some embodiments of the present disclosure.

Fig. 16A-16F are schematic cross-sectional views of stages of a process for attaching a light emitting cell to a substrate, according to some embodiments of the present disclosure.

Fig. 17A-17E are cross-sectional views of stages of a process for attaching a light emitting cell to a substrate, according to some embodiments of the present disclosure.

Element numbering in the figures:

100 to a substrate;

110-bonding pad;

200-light emitting units;

210-a light emitting section;

210A-a first surface;

210B-a second surface;

210S-side wall;

212-a semiconductor layer;

214 to a light emitting layer;

216-a semiconductor layer;

220-connecting part;

221, a conductive pad;

222-a first material layer;

222A-a first surface;

222B-a second surface;

223 to a second material layer;

224 to a bonding layer;

224A-a first surface;

224B-a second surface;

225 to a third material layer;

230 to a protection part;

232-reflecting layer;

240-light-taking structure;

250-transparent structure;

251-a first transparent layer;

252 to a second transparent layer;

253 to a third transparent layer;

260-high reflection metal layer;

271-nanoparticles;

272 to an adhesive layer;

281 to an organic layer;

282-aperture;

291-organic layer;

292 to nano particles;

300 to a substrate;

410-a first light emitting unit;

420 to a second light emitting unit;

430 to a third light emitting unit;

440 to a light-shielding layer;

450-a first filler;

460-second filler;

470G quantum dot film;

470R-quantum dot film;

480G to a color conversion improving layer;

480R to a color conversion improving layer;

490G filter film;

490R to the filter film;

500-protective layer;

505-wafer;

510 to a light emitting unit;

520-a reflecting layer;

530-stretching layer;

600-a substrate;

700-metal substrate;

1000-display equipment;

2000-display equipment;

b-blue pixel area;

e, heating process;

g-green pixel area;

r-red pixel region;

d1-spacing;

d2-spacing;

the X-direction;

y-direction.

Detailed Description

The following provides a detailed description of the assembly substrate, the display device, and the method of manufacturing the display device according to some embodiments of the present disclosure. It is to be understood that the following description provides many different embodiments, or examples, for implementing different aspects of some embodiments of the disclosure. The specific components and arrangements described below are merely illustrative of some embodiments of the disclosure for simplicity and clarity. These are, of course, merely examples and are not intended to be limiting of the disclosure. Moreover, repeated reference numerals or designations may be used in various embodiments. These iterations are merely provided for a simplified and clear description of some embodiments of the disclosure, and do not represent any correlation between the various embodiments and/or structures discussed. Furthermore, when a first material layer is located on or above a second material layer, the first material layer and the second material layer are in direct contact. Alternatively, one or more layers of other materials may be present, in which case there may not be direct contact between the first and second layers of material.

Furthermore, relative terms, such as "lower" or "bottom" and "upper" or "top," may be used in embodiments to describe one component's relative relationship to another component of the drawings. It will be understood that if the device of the drawings is turned upside down, components described as being on the "lower" side will be components on the "upper" side.

As used herein, the term "about", "about" or "substantially" generally means within 20%, preferably within 10%, and more preferably within 5%, or within 3%, or within 2%, or within 1%, or within 0.5% of a given value or range. The amounts given herein are approximate, that is, the meanings of "about", "about" and "about" may be implied without specifically stating "about", "about" or "about".

It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms, and these terms are only used to distinguish one element, component, region, layer and/or section from another element, component, region, layer and/or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of some embodiments of the present disclosure.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Some embodiments of the disclosure can be understood with reference to the accompanying drawings, which are also considered part of the description of the embodiments of the disclosure. It is to be understood that the drawings of the disclosed embodiments are not necessarily drawn to scale as actual devices or components may be illustrated. The shapes and thicknesses of the embodiments may be exaggerated in the drawings in order to clearly show the features of the embodiments of the present disclosure. Furthermore, the structures and devices in the drawings are schematically depicted in order to clearly illustrate the features of the embodiments of the present disclosure.

In some embodiments of the present disclosure, relative terms such as "lower," "upper," "horizontal," "vertical," "lower," "above," "top," "bottom," and the like are to be understood as referring to the segment and the orientation depicted in the associated drawings. These relative terms are for convenience of description only and do not imply that the described apparatus should be constructed or operated in a particular orientation. Terms concerning bonding, connecting, and the like, such as "connected," "interconnected," and the like, may refer to two structures as being in direct contact, or may also refer to two structures as not being in direct contact, unless otherwise specified, with another structure being interposed between the two structures. And the terms coupled and connected should also be construed to include both structures being movable or both structures being fixed.

It is noted that the term "substrate" may include devices already formed on a transparent substrate and various layers overlying the substrate, on which any desired plurality of active devices (transistor devices) may have been formed, although for simplicity of the drawing, this is only shown as a flat substrate.

The thickness of a structure described in the embodiments of the present disclosure represents the average thickness of the structure after the outlier (outlier) is removed. The outliers may be the thickness of the edges, distinct micro-grooves, or distinct micro-raised regions. After removing these outliers, the majority of the thickness values of the structure are within the range of plus or minus three standard deviations of the mean thickness value.

Referring to fig. 1A-1B, fig. 1A-1B are cross-sectional schematic views of a process of forming a bonding layer 224 with a high melting point for a display device 1000, according to some embodiments of the present disclosure. As shown in fig. 1A, the display apparatus 1000 includes a substrate 100 and a light emitting unit 200 disposed on the substrate 100. The substrate 100 is a substrate including an integrated circuit (not shown) electrically connected to the light emitting unit, such as a microprocessor, a memory device and/or other components. Integrated circuits may also include various passive and active components such as thin-film resistors (MIMCAPs), other types of capacitors such as Metal-insulator-Metal capacitors (MIMCAPs), inductors, diodes, Metal-Oxide-Semiconductor field-effect transistors (MOSFETs), complementary MOS transistors, Bipolar Junction Transistors (BJTs), laterally diffused MOS transistors, high power MOS transistors, thin-film transistors (thin-film transistors), or other types of transistors.

As shown in fig. 1A, in some embodiments, the substrate 100 includes a bonding pad 110 electrically and physically connected to the light emitting unit 200. The material of the bonding pad 110 includes copper, aluminum, molybdenum, tungsten, gold, chromium, nickel, platinum, titanium, iridium, rhodium, alloys thereof, combinations thereof, or other metal materials with good conductivity. The method of forming the bonding pad 110 includes a deposition process, a photolithography process, and an etching process. The deposition process may include Chemical Vapor Deposition (CVD), sputtering, resistive heating, electron beam, or any other suitable deposition method. In some embodiments of the present disclosure, the cvd process may be, for example, a low pressure cvd (low pressure chemical vapor deposition), a low temperature cvd (low temperature chemical vapor deposition), a Rapid Thermal Cvd (RTCVD), a Plasma Enhanced Chemical Vapor Deposition (PECVD), an Atomic Layer Deposition (ALD), or other conventional processes, but is not limited thereto. The photolithography process may include photoresist coating (e.g., spin coating), soft baking, mask alignment, exposure, post exposure baking, developing the photoresist, rinsing, drying (e.g., hard baking), other suitable processes, or combinations thereof. Alternatively, the photolithography process may be performed or replaced by other suitable methods, such as maskless lithography, electron-beam writing (electron-beam writing), and ion-beam writing (ion-beam writing). The etching process includes dry etching, wet etching or other etching methods, but is not limited thereto.

As shown in fig. 1A, in some embodiments, the light emitting unit 200 includes a light emitting portion 210, a protection portion 230, a conductive pad 221 including a connection portion 220 electrically connected to a bonding pad 110 of a substrate 100, a first material layer 222, and a second material layer 223. As shown in fig. 1A, the light-emitting portion 210 includes a semiconductor layer 212, a light-emitting layer 214, and a semiconductor layer 216. The semiconductor layer 212 and the semiconductor layer 216 are connected to the conductive pad 221. The semiconductor layer 212 and the semiconductor layer 216 may be elemental semiconductors including amorphous silicon (amorphous-Si), polycrystalline silicon (poly-Si), germanium (germanium); compound semiconductors including gallium nitride (GaN), silicon carbide (silicon carbide), gallium arsenide (gallium arsenide), gallium phosphide (gallium phosphide), indium phosphide (indium phosphide), indium arsenide (indium arsenide), and/or indium antimonide (indium antimonide); an alloy semiconductor including a silicon germanium alloy (SiGe), a gallium arsenic phosphide (GaAsP), an aluminum indium arsenide (AlInAs), an aluminum gallium arsenide (AlGaAs), an indium gallium arsenide (GaInAs), a gallium indium phosphide (GaInP), and/or a gallium indium arsenide phosphide (GaInAsP); metal oxides including Indium Gallium Zinc Oxide (IGZO), Indium Zinc Oxide (IZO), indium gallium tin zinc oxide (IGZTO); organic semiconductors, including polycyclic aromatic compounds, or combinations of the above, and are not limited thereto.

As shown in fig. 1A, the light emitting layer 214 is disposed between the semiconductor layer 212 and the semiconductor layer 216. The light emitting layer 214 may include a homojunction (homojunction), a heterojunction (heterojunction), a single-quantum well (SQW), a multiple-quantum well (MQW), or other similar structures. In some embodiments, the light emitting layer 214 comprises undoped n-type In_xGa_(1-x)And N is added. In other embodiments, the light emitting layer 214 may comprise, for example, Al_xIn_yGa_(1-x-y)N, other commonly used materials. In addition, the light emitting layer 214 may be a multiple quantum well structure including multiple well layers (e.g., InGaN) and barrier layers (e.g., GaN) alternately arranged. The light-emitting layer 214 may be formed by Metal Organic Chemical Vapor Deposition (MOCVD), Molecular Beam Epitaxy (MBE), Hydride Vapor Phase Epitaxy (HVPE), Liquid Phase Epitaxy (LPE), or other suitable cvd methods.

As shown in fig. 1A, the protection part 230 is disposed on the side of the light emitting part 210, and surrounds the light emitting part 210 and the conductive pad 221. The protection part 230 is disposed on the light-emitting path and has the effect of changing the light-emitting shape or improving the light-emitting efficiency. In some embodiments, the material of the protection part 230 may be a metal material, and may be the same as or similar to the material of the bonding pad 110 described above.

As shown in fig. 1A, the conductive pad 221 is adjacent to the light emitting portion 210. The conductive pad 221 may be made of copper, aluminum, molybdenum, tungsten, gold, chromium, nickel, platinum, titanium, iridium, rhodium, alloys thereof, combinations thereof, or other metal materials with good conductivity, but not limited thereto.

As shown in fig. 1A, the first material layer 222 is adjacent to the bonding pad 110. The material of the first material layer 222 may be a low melting point alloy material. In some embodiments, the first material layer 222 is a eutectic material with a melting point less than 300 ℃, such as an indium tin alloy, a zinc tin alloy, a silver tin alloy, an indium gold alloy, a tin gold alloy, or other suitable material.

As shown in fig. 1A, in some embodiments, the light emitting cell 200 further includes a second material layer 223 disposed between the conductive pad 221 and the first material layer 222. The second material layer 223 may serve as a buffer layer, and in a subsequent process of applying temperature and pressure to the display apparatus 1000, the first material layer 222 and the second material layer 223 are co-melted to form a bonding layer having a higher melting point than the first material layer 222. In some embodiments, the second material layer 223 may be a single layer or a multi-layer stack structure, and when the second material is a single layer, the second material layer 223 includes gold (Au), silver (Ag), copper (Cu), nickel (Ni), platinum (Pt), tin (Sn), palladium (Pt), or an alloy thereof, or a multi-layer stack structure formed of the alloy thereof, for example: copper/nickel/gold or copper/nickel/palladium/gold, etc.

Next, in some embodiments, pressure and temperature are applied to the structure shown in fig. 1A to fuse the first material layer 222 and the second material layer 223. During the application of pressure and temperature, the material of the second material layer 223 diffuses into the first material layer 222 through the first surface 222A of the first material layer 222, thereby forming the structure shown in fig. 1B. In some embodiments, the temperature of the application is in the range of 100 ℃ to 400 ℃. In some embodiments, the pressure applied is between 0.1MPa and 100 MPa.

Referring to fig. 1B, after applying pressure and temperature to the structure shown in fig. 1A, the first material layer 222 and the second material layer 223 form a bonding layer 224. In some embodiments, the bonding layer 224 includes a material composition of the first material layer 222 consisting essentially of the first component and a second material layer 223 consisting essentially of the second component. Also, the bonding layer 224 has a higher melting point than the first material layer 222. In some embodiments, the melting point of the bonding layer 224 is in the range of 100 ℃ to 500 ℃. In some embodiments, the bonding layer 224 has a melting point in the range of 350 ℃ to 400 ℃, which may also be 100 ℃ to 350 ℃.

In addition, since the second material layer 223 diffuses into the first material layer 222 through the first surface 222A of the first material layer 222, the material of the second material layer 223 is not uniformly distributed in the bonding layer 224. That is, the second component is not uniformly distributed within bonding layer 224. 1B-1C, FIG. 1C is a graph illustrating a concentration profile of a second component in a direction (e.g., Y-direction) from a first surface 224A of a bonding layer 224 toward a second surface 224B in FIG. 1B, according to some embodiments of the present disclosure. As shown in FIG. 1C, the concentration of the second component decreases and the concentration of the first component increases from the first surface 224A toward the second surface 224B of the bonding layer 224, such that the concentrations of the first and second components of the bonding layer are in opposite trends.

In fig. 1C, the maximum value of the concentration of the second component is defined as 100, and the maximum value without the second component is defined as 0. Since the second material layer 223 is disposed over the first material layer 222, the concentration of the second component is greatest at the interface of the second material layer 223 and the first material layer 222 (i.e., the first surface 224A of the bonding layer 224) and is least at the interface of the first material layer 222 and the bond pad 110 (i.e., the second surface 224B of the bonding layer 224). Although fig. 1C depicts a concentration of the second component at the second surface 224B of the bonding layer 224 as 0, the disclosure is not so limited. In other embodiments, the concentration of the second component is not 0 at the second surface 224B of the bonding layer 224.

As shown in fig. 1B, the bonding layer 224 and the conductive pad 221 may serve as the connection portion 220 of the light emitting unit 200. Since the bonding layer 224 has a higher melting point, the structure of the connection portion is not damaged by high temperature in the subsequent process, so that the light emitting unit 200 and the substrate 100 cannot be electrically connected. Therefore, the formation of the bonding layer 224 helps to improve the production yield of the display apparatus 1000.

Referring to fig. 2A-2B, fig. 2A-2B are cross-sectional schematic views of a process of forming a display device 1000 having a bonding layer 224 with a high melting point, according to some embodiments of the present disclosure. In some embodiments, as shown in fig. 2A, the display device 1000 includes a second material layer 223 disposed on the first surface 222A of the first material layer 222, and a third material layer 225 disposed on the second surface 222B of the first material layer 222, respectively. In some embodiments, the third material layer 225 includes gold, silver, copper, nickel, platinum, tin, palladium, or alloys thereof. In some embodiments, the material of the third material layer 225 is the same as the material of the second material layer 223, and in other embodiments, the material of the third material layer 225 is different from the material of the second material layer 223, wherein the third material layer 225 and the second material layer 223 may be a single-layer structure or a multi-layer stack structure. Next, in some embodiments, pressure and temperature are applied to the structure shown in fig. 2A to fuse the first material layer 222, the second material layer 223, and the third material layer 225. During the application of pressure and temperature, the material of the second material layer 223 diffuses into the first material layer 222 through the first surface 222A of the first material layer 222, and the material of the third material layer 225 diffuses into the first material layer 222 through the second surface 222B of the first material layer 222, thereby forming the structure shown in fig. 2B. In some embodiments, the temperature of the application is in the range of 100 ℃ to 400 ℃. In some embodiments, the pressure applied is in the range of 0.1MPa to 100 MPa.

Referring to fig. 2B, after applying pressure and temperature to the structure shown in fig. 2A, the first material layer 222, the second material layer 223, and the third material layer 225 form a bonding layer 224. In some embodiments, the bonding layer 224 includes a first component composed of the material of the first material layer 222 and a second component composed of the material of the second material layer 223 and the third material layer 225. Also, the bonding layer 224 has a higher melting point than the first material layer 222. In some embodiments, the melting point of the bonding layer 224 is in the range of 100 ℃ to 500 ℃. In some embodiments, the bonding layer 224 has a melting point in the range of 350 ℃ to 400 ℃, and may also be 100 ℃ to 350 ℃.

In addition, the second material layer 223 is diffused into the first material layer 222 through the first surface 222A of the first material layer 222, and the third material layer 225 is diffused into the first material layer 222 through the second surface 222B of the first material layer 222. The materials of the second material layer 223 and the third material layer 225 are not uniformly distributed in the bonding layer 224. That is, the second component is not uniformly distributed within bonding layer 224. 2B-2C, FIG. 2C is a graph illustrating a concentration profile of a second component in a direction from first surface 224A toward second surface 224B of bonding layer 224 in FIG. 2B, according to some embodiments of the present disclosure. As shown in fig. 2C, if the material of the second material layer 223 is the same as that of the third material layer 225, the concentration distribution of the second component is not decreased or increased in a direction from the first surface 224A of the bonding layer 224 to the second surface 224B.

In fig. 2C, the maximum value of the concentration of the second component is defined as 100, and the maximum value without the second component is defined as 0. Since the second material layer 223 is disposed above the first material layer 222 and the third material layer 225 is disposed below the first material layer 222, the concentration of the second component is at a maximum at the interface of the second material layer 223 and the first material layer 222 (i.e., the first surface 224A of the bonding layer 224) and the interface of the third material layer 225 and the first material layer 222 (i.e., the second surface 224B of the bonding layer 224). Additionally, a minimum value of the concentration of the second component is located between the first surface 224A and the second surface 224B. Although fig. 2C depicts the concentration of the second component being the same at the first surface 224A and the second surface 224B of the bonding layer 224, the disclosure is not so limited. In other embodiments, the concentration of the second component at the first surface 224A of the bonding layer 224 is different than the concentration of the second component at the second surface 224B.

Referring to fig. 3A-3B, fig. 3A-3B are cross-sectional schematic views of a process of forming a display device 1000 having a bonding layer 224 with a high melting point, according to some embodiments of the present disclosure. In some embodiments, as shown in fig. 3A, a third material layer 225 may be used as a bonding pad of the substrate 100 instead of the bonding pad 110 on the substrate 100. Next, in some embodiments, for the structure shown in fig. 3A, pressure and temperature are applied to fuse the second material layer 223, the third material layer 225 and the first material layer 222 together. During the application of pressure and temperature, the material of the second material layer 223 diffuses into the first material layer 222 through the first surface 222A of the first material layer 222, and the material of the third material layer 225 diffuses into the first material layer 222 through the second surface 222B of the first material layer 222, thereby forming the structure shown in fig. 3B. In some embodiments, the temperature of the application is in the range of 100 ℃ to 400 ℃. In some embodiments, the pressure applied is in the range of 0.1MPa to 100 MPa.

Referring to fig. 3B, after applying pressure and temperature to the structure shown in fig. 3A, the first material layer 222, the second material layer 223, and the third material layer 225 form a bonding layer 224. In some embodiments, the bonding layer 224 includes a first component composed of the material of the first material layer 222 and a second component composed of the material of the second material layer 223 and the third material layer 225. Also, the bonding layer 224 has a higher melting point than the first material layer 222. In some embodiments, the bonding layer 224 has a melting point in the range of 300 ℃ to 500 ℃. In some embodiments, the bonding layer 224 has a melting point in the range of 350 ℃ to 400 ℃, or 100 ℃ to 350 ℃.

In addition, the second material layer 223 is diffused into the first material layer 222 through the first surface 222A of the first material layer 222, and the third material layer 225 is diffused into the first material layer 222 through the second surface 222B of the first material layer 222. The materials of the second material layer 223 and the third material layer 225 are not uniformly distributed in the bonding layer 224. That is, the second component is not uniformly distributed within bonding layer 224. 3B-3C, FIG. 3C is a graph illustrating a concentration profile of a second component in a direction from first surface 224A toward second surface 224B of bonding layer 224 in FIG. 3B, according to some embodiments of the present disclosure. As shown in fig. 3C, if the material of the second material layer 223 is the same as that of the third material layer 225, the concentration distribution of the second component is not decreased or increased in a direction from the first surface 224A of the bonding layer 224 to the second surface 224B.

In fig. 3C, the maximum value of the concentration of the second component is defined as 100, and the maximum value without the second component is defined as 0. Since the second material layer 223 is disposed above the first material layer 222 and the third material layer 225 is disposed below the first material layer 222, the concentration of the second component is at a maximum at the interface between the second material layer 223 and the first material layer 222 (i.e., the first surface 224A of the bonding layer 224) and the interface between the third material layer 225 and the first material layer 222 (i.e., the second surface 224B of the bonding layer 224), and the minimum of the concentration of the second component is between the first surface 224A and the second surface 224B. Although fig. 3C depicts the concentration of the second component being the same at the first surface 224A and the second surface 224B of the bonding layer 224, the disclosure is not so limited. In other embodiments, the concentration of the second component at the first surface 224A of the bonding layer 224 is different than the concentration of the second component at the second surface 224B.

In this embodiment, the bonding pads on the substrate and the first material layer on the substrate are directly fused together, thereby simplifying the process. Therefore, the yield of the display apparatus 1000 can be improved and the cost can be reduced. In addition, in this embodiment, substantially no interface exists between the bonding pads of the substrate and the bonding layer.

In some embodiments, the light emitting unit 200 is a micro light emitting diode (μ LED). For example, as shown in fig. 1A, the total thickness of the semiconductor layer 212, the light emitting layer 214 and the semiconductor layer 216 is in a range of 1 μm to 20 μm, and in some embodiments, the total thickness of the semiconductor layer 212, the light emitting layer 214 and the semiconductor layer 216 is in a range of 3 μm to 10 μm, and further in a range of 3 μm to 5 μm.

Referring to fig. 4, fig. 4 is a schematic cross-sectional view of a display device 1000 according to some embodiments of the present disclosure. In some embodiments, the surface of the second material layer 223 adjacent to the first material layer 222 may have a concave-convex structure. In this embodiment, when pressure and temperature are applied to the structure shown in fig. 4, the second component has a non-uniform concentration distribution not only in the Y direction but also in the X direction. Although fig. 4 illustrates that the pitch of the concave-convex structure on the surface of the second material layer 223 is fixed, the disclosure is not limited thereto. In other embodiments, the pitch of the concave-convex structure of the surface of the second material layer 223 is irregular, and the shape of the concave-convex structure may be any irregular shape.

Referring to fig. 5, fig. 5 is a schematic cross-sectional view of a display apparatus 1000 according to some embodiments of the present disclosure. In some embodiments, as shown in fig. 5, the first surface 210A of the light emitting portion 210 has a light extraction structure 240. The light extraction structure 240 can be formed by directly performing an etching process on the first surface 210A of the light emitting part 210, so that the light extraction structure 240 and the light emitting part 210 are formed of the same material. Although fig. 5 illustrates that the pitch of the light extraction structures 240 is fixed, the disclosure is not limited thereto. In other embodiments, the pitch of the light extraction structures 240 is irregular, and the shape of the light extraction structures 240 may be any irregular shape. In some embodiments, the roughness of the light extraction structure 240 is greater than 0.2 μm. In this embodiment, the light extraction efficiency can be improved by roughening the surface (e.g., the first surface 210A) of the light emitting part 210.

Referring to fig. 6, fig. 6 is a schematic cross-sectional view of a display apparatus 1000 according to some embodiments of the present disclosure. In some embodiments, as shown in fig. 6, the light extraction structure 240 of the first surface 210A of the light emitting part 210 is a different material layer than the light emitting part 210. The light-extracting structure 240 may be formed by depositing a material layer (not shown) on the first surface 210A of the light-emitting portion 210, and then performing an etching process on the material layer. Although fig. 6 shows that the pitch of the light extraction structures 240 is fixed, the disclosure is not limited thereto. In other embodiments, the pitch of the light extraction structures 240 is irregular, and the shape of the light extraction structures 240 may be any irregular shape.

In this embodiment, the refractive index of the light extraction structure 240 is less than 2.4, and less than the refractive index of the light emitting portion 210. In some embodiments, the material of the light extracting structure 240 is a transparent material, such as Indium Tin Oxide (ITO), Tin Oxide (TO), Indium Zinc Oxide (IZO), Indium Gallium Zinc Oxide (IGZO), Indium Tin Zinc Oxide (ITZO), Antimony Tin Oxide (ATO), Antimony Zinc Oxide (AZO), a combination of the above materials or any other suitable transparent conductive oxide material, or a high polymer material with a refractive index less than 2.4, such as: optical resin, epoxy resin (epoxy), silicone resin (silicone), and the like, without being limited thereto. In this embodiment, after the material layer with a smaller refractive index is deposited on the first surface 210A of the light emitting portion 210, the light emitting efficiency of the light emitting portion 210 can be improved.

Referring to fig. 7, fig. 7 is a schematic cross-sectional view of a display device 1000 according to some embodiments of the present disclosure. In some embodiments, as shown in fig. 7, the protection portion 230 of the light emitting unit 200 further includes a reflective layer 232. The reflective layer 232 is disposed under the second surface 210B of the light emitting part 210, and is disposed on sidewalls of the light emitting layer 214, the semiconductor layer 216, and a portion of the conductive pad 221. The reflective layer 232 can be a bragg reflector (ODR) or an omni-directional reflector (ODR), and the material thereof can be a non-metal material, an insulating material or a white photoresist, and in some embodiments, the reflective layer 232 can be SiO₂The refractive index of the low refractive index insulating layer material or the high refractive index insulating layer material of SiN, TiO2 may be adjusted according to the process conditions or the composition ratio, and thus is not limited to the above materials.

Referring to fig. 8, fig. 8 is a schematic cross-sectional view of a display device 1000 according to some embodiments of the present disclosure. In some embodiments, as shown in fig. 8, the display apparatus 1000 further includes a transparent structure 250 disposed over the first surface 210A. In some embodiments, as shown in FIG. 8, the transparent structure 250 is a transparent layer having a refractive index of less than 2.4. In this embodiment, after the transparent structure 250 with a smaller refractive index is deposited on the first surface 210A of the light emitting part 210, the light emitting efficiency of the light emitting part 210 can be improved.

Referring to fig. 9, fig. 9 is a schematic cross-sectional view of a display device 1000, according to some embodiments of the present disclosure. In some embodiments, as shown in fig. 9, the transparent structure 250 includes a first transparent layer 251, a second transparent layer 252, and a third transparent layer 253. The first transparent layer 251 is disposed over the first surface 210A of the light emitting portion 210, the second transparent layer 252 is disposed over the first transparent layer 251, and the third transparent layer 253 is disposed over the second transparent layer 252. In some embodiments, the refractive index of the third transparent layer 253 is less than the refractive index of the second transparent layer 252, the refractive index of the second transparent layer 252 is less than the refractive index of the first transparent layer 251, and the refractive index of the first transparent layer 251 is less than the refractive index of the semiconductor layer 212.

Although fig. 9 illustrates that the transparent structure 250 includes 3 transparent layers, the disclosure is not limited thereto. In other embodiments, the transparent structure 250 includes 2 or more transparent layers, and the refractive index of the transparent layers decreases with distance from the first surface 210A of the light emitting portion 210. In this embodiment, after the transparent structure 250 having a gradient refractive index is deposited on the first surface 210A of the light emitting part 210, the light extraction efficiency of the light emitting part 210 can be improved.

Referring to fig. 10, fig. 10 is a schematic cross-sectional view of a display apparatus 1000 according to some embodiments of the present disclosure. In some embodiments, as shown in fig. 10, the sidewall 210S of the light emitting portion 210 has an inclined sidewall in the Y direction. The sidewall 210S having the inclination may be formed by performing an etching process on the semiconductor layer 212, the light emitting layer 214 and the semiconductor layer 216. In this embodiment, the light emitting section 210 having the inclined side wall 210S is formed, and the light emitting efficiency of the light emitting section 210 can be improved.

Referring to fig. 11, fig. 11 is a schematic cross-sectional view of a display device 1000 according to some embodiments of the present disclosure. In some embodiments, as shown in fig. 11, the display device 1000 further includes a highly reflective metal layer 260 disposed between the light emitting part 210 and the protection part 230. More specifically, the highly reflective metal layer 260 is disposed within the protective part 230, and between the semiconductor layers 212 and 216 and the conductive pad 221. In this embodiment, the high reflective metal layer 260 has a reflectivity greater than 80%, and is made of, for example, aluminum, silver, or other metal with a reflectivity greater than 80%. In this embodiment, the highly reflective metal layer 260 having a reflectivity greater than 80% is formed, so that the light extraction efficiency of the light emitting part 210 can be improved.

Referring to fig. 12, fig. 12 is a block diagram of some embodiments according to the present disclosureA schematic cross-sectional view of the device 1000 is shown. In some embodiments, as shown in fig. 12, transparent structure 250 comprises nanoparticles 271 and adhesion layer 272. In this embodiment, the transparent structure 250 can fix the position of the nanoparticles 271 by spraying the nanoparticles 271 on the first surface 210A of the light emitting part 210 and then coating the adhesive layer 272. The material of the nanoparticles 271 comprises zirconium oxide (ZrO)₂) Titanium oxide (TiO)₂) Silicon oxide (SiO)₂) Oxide group (Ta)₂O₅) Tungsten oxide (WO)₃) Yttrium oxide (Y)₂O₃) Cerium oxide (CeO)₂) Antimony oxide (Sb)₂O₃) Niobium oxide (Nb)₂O₅) Boron oxide (B)₂O₃) Alumina (Al)₂O₃) Zinc oxide (ZnO), indium oxide (In)₂O₃) Cerium fluoride (CeF)₃) Magnesium fluoride (MgF)₂) Calcium fluoride (CaF)₂) Combinations of the above, or other suitable nano metal oxides.

The material of the Adhesive layer 272 may include an Optically Clear Adhesive (OCA), an Optically Clear Resin (OCR), or other suitable transparent Adhesive material, but is not limited thereto. In this embodiment, the nanoparticles 271 are sprayed on the first surface 210A of the light-emitting portion 210, so as to increase the haze (haze) of the first surface 210A, thereby improving the light-emitting efficiency of the light-emitting portion 210.

Referring to fig. 13, fig. 13 is a schematic cross-sectional view of a display device 1000, according to some embodiments of the present disclosure. In some embodiments, as shown in fig. 13, the transparent structure 250 includes an organic layer 281 and an aperture 282. The organic layer 281 is disposed above the first surface 210A of the light emitting part 210, and the pores 282 are distributed in the organic layer 281. As shown in fig. 13, the distribution density of the voids 282 increases from the second surface 210B of the light-emitting portion 210 toward the first surface 210A. More specifically, the distribution density of the pores 282 is lowest near the first surface 210A of the light emitting portion 210, and increases with distance from the first surface 210A. In some embodiments, air or other inert gas is within the aperture 282.

The material of the organic layer 281 may include polymethyl methacrylate (PMMA), Polycarbonate (PC), Polyimide (PI), or other suitable polymer. The pores 282 may be formed by soaking the organic layer 281 in an organic solvent, such as ethanol, to expand the pores in the organic layer 281. In this embodiment, since the distribution density of the pores 282 is increased with distance from the first surface 210A, the refractive index of the transparent structure 250 becomes smaller with distance from the first surface 210A of the light emitting part 210. In this embodiment, after the transparent structure 250 having a gradient refractive index is formed on the first surface 210A of the light emitting part 210, the light extraction efficiency of the light emitting part 210 can be improved.

Referring to fig. 14, fig. 14 is a cross-sectional schematic view of a display device 1000, according to some embodiments of the present disclosure. In some embodiments, as shown in fig. 14, the transparent structure 250 includes an organic layer 291 and nanoparticles 292. The organic layer 291 is disposed above the first surface 210A of the light emitting portion 210, and the nanoparticles 292 are distributed in the organic layer 291. As shown in fig. 14, the distribution density of the nanoparticles 292 decreases in the direction from the second surface 210B of the light-emitting portion 210 to the first surface 210A. More specifically, the distribution density of the nanoparticles 292 is the greatest near the first surface 210A of the light emitting portion 210, and becomes lower as the distance from the first surface 210A increases.

The materials of the organic layer 291 and the nanoparticles 292 may be the same as or similar to the materials of the organic layer 281 and the nanoparticles 271, respectively, and will not be described again. In this embodiment, the transparent structure 250 can be formed by immersing the organic layer 291 in an organic solvent containing the nanoparticles 292 such that the nanoparticles 292 replace the holes in the organic layer 291. In this embodiment, since the distribution density of the nanoparticles 292 is decreased as being distant from the first surface 210A, the refractive index of the transparent structure 250 is decreased as being distant from the first surface 210A of the light emitting part 210. In this embodiment, after the transparent structure 250 having a gradient refractive index is formed on the first surface 210A of the light emitting part 210, the light extraction efficiency of the light emitting part 210 can be improved.

Referring to fig. 15, fig. 15 is a schematic cross-sectional view of a light emitting unit 2000 according to some embodiments of the present disclosure. As shown in fig. 15, the light emitting unit 2000 has a blue pixel region B, a green pixel region G and a red pixel region R corresponding to different light emitting wavelengths. As shown in fig. 15, the light emitting unit 2000 includes a first light emitting unit 410, a second light emitting unit 420, and a third light emitting unit 430 disposed on the substrate 300. The substrate 300 may be the same as or similar to the substrate 100 described above, and will not be repeated here. The first light emitting unit 410 is disposed in the blue pixel region B and surrounded by the first filler 450. The material of the first filler 450 may include silicone, epoxy, polymethyl methacrylate, polycarbonate, or other suitable materials. The light emitting unit 2000 also includes a second filler 460 disposed on the first filler 450 and located in the blue pixel region B. The material of the second filler 460 may be the same as or different from the first filler 450. In some embodiments, the refractive index of the second filler 460 is less than the refractive index of the first filler 450. It is noted that some components of the first light emitting unit 410, the second light emitting unit 420, and the third light emitting unit 430 are omitted for simplicity, but the disclosure is not limited thereto. In other embodiments, the structures of the first light emitting unit 410, the second light emitting unit 420, and the third light emitting unit 430 may be the same as or similar to the light emitting unit 200 according to the embodiment of the invention.

As shown in fig. 15, the second light emitting unit 420 and the third light emitting unit 430 are respectively disposed in the green pixel region G and the red pixel region R, and are surrounded by the first filler 450. In addition, the light emitting unit 2000 also includes a quantum dot thin film 470G and a quantum dot thin film 470R respectively disposed on the second light emitting unit 420 and the third light emitting unit 430. The materials of the quantum dot film 470G and the quantum dot film 470R may include an organic layer or an inorganic layer doped with quantum dots (quantum dots), which are nano-three-dimensional structures comprising a component including zinc, cadmium, selenium, sulfur, or a combination thereof. The particle size of the quantum dot is about 1nm-10 nm. By adjusting the particle size of the quantum dots, the spectrum of light generated after the light emitted by the second light emitting unit 420 or the third light emitting unit 430 is excited can be changed. For example, the quantum dot film 470G doped with quantum dots of the first particle size may generate green light after being excited by blue light, and the quantum dot film 470R doped with quantum dots of the second particle size may generate red light after being excited by blue light.

As shown in fig. 15, the light emitting unit 2000 also includes a color conversion enhancing layer 480G and a color conversion enhancing layer 480R respectively disposed on the quantum dot thin film 470G and the quantum dot thin film 470R. The color conversion enhancing layer 480G and the color conversion enhancing layer 480R may be, for example, materials that reflect blue light, which may reflect non-excited blue light back to the quantum dot thin film 470R or the quantum dot thin film 470G, respectively, so as to enhance the efficiency of the blue light excited by the quantum dot thin film 470R or the quantum dot thin film 470G to generate light of other colors. As shown in fig. 15, the light emitting unit 2000 also includes a filter 490G and a filter 490R disposed on the color conversion enhancing layer 480G and the color conversion enhancing layer 480R, respectively. The filter 490G and the filter 490R may include a blue filter, a red filter, a green filter, or combinations thereof.

In addition, as shown in fig. 15, the light emitting diode 2000 further includes a protection layer 500. The passivation layer 500 is disposed over the second filler 460, the filter 490G and the filter 490R. The protective layer 500 may comprise a transparent substrate, which may be, for example, a glass substrate, a ceramic substrate, a plastic substrate, or any other suitable transparent substrate. The passivation layer 500 may also include phosphosilicate glass (PSG), borophosphosilicate glass (BPSG), silicon oxide, silicon nitride, silicon oxynitride, and high-k dielectric material. The high-k dielectric material may be a metal oxide, a metal nitride, a metal silicide, a transition metal oxide, a transition metal nitride, a transition metal silicide, a metal oxynitride, a metal aluminate, a zirconium silicate, or a zirconium aluminate. For example, the high-k dielectric material can be LaO, AlO, ZrO, TiO, Ta₂O₅、Y₂O₃、SrTiO₃(STO)、BaTiO₃(BTO)、BaZrO、HfO₂、HfO₃、HfZrO、HfLaO、HfSiO、HfSiON、LaSiO、AlSiO、HfTaO、HfTiO、HfTaTiO、HfAlON、(Ba,Sr)TiO₃(BST)、Al₂O₃Or a combination of the foregoing.

As shown in fig. 15, the light emitting unit 2000 includes a light shielding layer 440 disposed between the substrate 300 and the protection layer 500. The light-shielding layer 440 separates the blue pixel region B, the green pixel region G, and the red pixel region R. The light-shielding layer 440 is used to shield the regions or components of the light-emitting unit 2000 that are not used for displaying colors, such as scan lines and data lines. The material of the light-shielding layer 440 may be black photoresist, black printing ink, black resin, or any other suitable light-shielding material and light-shielding color, wherein the light-shielding material and light-shielding color mainly refer to blocking light from penetrating, and is not limited to light absorption, and may also be a light-shielding material and light-shielding color with high reflection, and the light-shielding color may be a high-concentration white material, or may not be limited to a single material constituting the structure, and may also be a transparent material with a high-reflectivity metal coated on the periphery, and the like, without being limited thereto.

In some embodiments, the first light emitting unit 410, the second light emitting unit 420, and the third light emitting unit 430 all emit blue light (e.g., light with a wavelength of 380-500 nm), but the dominant wavelengths (dominant wavelengths) emitted by the three units are different. The main wavelength is a wavelength having the strongest intensity among wavelengths of light emitted from the light emitting unit. In some embodiments, the dominant wavelength of light emitted from the second light emitting unit 420 is less than the dominant wavelength of light emitted from the first light emitting unit 410 by more than 2nm, and the dominant wavelength of light emitted from the third light emitting unit 430 is greater than the dominant wavelength of light emitted from the first light emitting unit 410 by more than 2 nm. In this embodiment, the difference between the dominant wavelength of the light emitted from the third light emitting unit 430 and the dominant wavelength of the light emitted from the second light emitting unit 420 is greater than 4 nm. In other embodiments, the difference between the dominant wavelength of the light emitted from the third light emitting unit 430 and the dominant wavelength of the light emitted from the second light emitting unit 420 is greater than 10 nm. In this embodiment, the second light emitting unit 420 having a smaller dominant wavelength of emitted light is disposed in the green pixel region G, and the third light emitting unit 430 having a larger dominant wavelength of emitted light is disposed in the red pixel region R, so that the phenomenon of uneven light source (mura) caused by different dominant wavelengths of emitted light can be avoided only by converting the quantum dot film 470G and the quantum dot film 470R, respectively. Therefore, the light emitting units outside the specification can be utilized more to avoid waste, so as to reduce the production cost of the light emitting unit 2000.

In some embodiments, the first light emitting unit 410, the second light emitting unit 420, and the third light emitting unit 430 all emit blue light, but the dominant wavelengths emitted by the three are different. In some embodiments, the dominant wavelength of light emitted by the second light emitting unit 420 is less than the dominant wavelength of light emitted by the first light emitting unit 410 by more than 5nm, and the dominant wavelength of light emitted by the third light emitting unit 430 is less than the dominant wavelength of light emitted by the first light emitting unit 410 by more than 5 nm. In this embodiment, the quantum dot thin film 470G and the quantum dot thin film 470R have higher absorption of short wavelength light, and thus have better light emitting efficiency. Therefore, the light emitting units outside the specification can be utilized more to avoid waste, so as to reduce the production cost of the light emitting unit 2000.

In some embodiments, the first light emitting unit 410 emits blue light, the second light emitting unit 420 emits green light (e.g., light with a wavelength of 500-580 nm), and the third light emitting unit 430 emits blue light or ultraviolet light. Since the light emitting unit emitting red light is difficult to be formed on the substrate 300 by a flip chip (flip chip) technique, the third light emitting unit 430 emitting blue light or ultraviolet light and the quantum dot film 470R can be used to emit red light, so as to solve the above-mentioned process problem.

In some embodiments, the first light emitting unit 410 emits blue light, the second light emitting unit 420 emits blue light or ultraviolet light, and the third light emitting unit 430 emits red light (e.g., light with a wavelength of 600-780 nm). Since the light emitting unit emitting green light has a wide full width at half maximum (FWHM), the intensity of the emitted green light is made small. Therefore, the third light emitting unit 430 emitting blue or ultraviolet light and the quantum dot film 470G emitting green light can solve the above problems.

Referring to fig. 16A-16F, fig. 16A-16F are schematic cross-sectional views of stages of a process for attaching the light emitting cell 510 to the substrate 600, according to some embodiments of the present disclosure. First, as shown in fig. 16A, a wafer 505 is provided, and a plurality of light emitting cells 510 are formed on the wafer 505, wherein a distance between every two adjacent light emitting cells 510 is D1. Wafer 505 may be, for example, a sapphire substrate composed of aluminum oxide with gallium nitride formed thereover. It is noted that some components of the light emitting unit 510 are omitted for brevity, but the present disclosure is not limited thereto. In other embodiments, the structure of the light emitting unit 510 may be the same as or similar to the light emitting unit 200 according to the embodiment of the present invention.

Next, in some embodiments, as shown in fig. 16B, a reflective layer 520 is coated on the wafer 505. The reflective layer 520 is used to block ultraviolet rays or absorb energy of ultraviolet rays in a subsequent Laser Lift Off (LLO) process. The material of the reflective layer 520 may include barium sulfate, magnesium fluoride, magnesium oxide, aluminum oxide, titanium oxide, lanthanum oxide, germanium oxide, tellurium oxide, erbium oxide, zirconium oxide, a combination thereof, or other materials capable of reflecting ultraviolet light, or metal materials such as gold (Au), silver (Ag), titanium (Ti), nickel (Ni), and aluminum (Al). The reflective layer 520 may be formed by spin coating or other processes.

Next, in some embodiments, as shown in FIG. 16C, a stretching layer 530 is formed on the reflective layer 520. In some embodiments, the stretch layer 530 surrounds the light emitting unit 510, and covers surfaces of the light emitting layer and the semiconductor layer of the light emitting unit 510. The material of the elastic layer 530 includes polymethyl methacrylate, polycarbonate polyimide, or other polymers having elasticity. Although fig. 16C illustrates that the light emitting unit 510 is not completely covered by the stretchable layer 530 (e.g., the conductive pad of the light emitting unit 510 is not covered), the disclosure is not limited thereto. In other embodiments, the stretch layer 530 completely covers the light emitting unit 510.

Next, in some embodiments, as shown in fig. 16D, the wafer 505 and the reflective layer 520 are removed from the light emitting unit 510. The method of removing the wafer 505 may use a laser stripping process, and after removing the wafer 505 from the light emitting unit 510, the reflective layer 520 may be removed using an etching process.

Next, in some embodiments, as shown in FIG. 16E, the stretching layer 530 is extended by an extension process. The extension process includes a single-axis extension (uniaxial extension) process, a bi-axis extension (bi-axis extension) process, or other suitable processes.

Next, in some embodiments, as shown in fig. 16E, after the stretchable layer 530 is extended, the light emitting unit 510 is attached to the substrate 600. After the extension process shown in fig. 16D, the distance between two adjacent light emitting cells 510 becomes D2 greater than D1. The material of the substrate 600 may be the same as or similar to the substrate 100 described above, and will not be repeated here. In this embodiment, after the wafer 505 is removed, the pitch of each light emitting unit 510 is increased. Therefore, when the light emitting cells 510 are initially formed on the wafer 505, more light emitting cells 510 may be formed at a smaller pitch, without setting the pitch of the light emitting cells 510 to a desired pitch when the light emitting cells 510 are initially formed. Therefore, more light emitting cells 510 can be formed on a unit area of the wafer 505, and the production cost can be reduced.

Referring to fig. 17A-17E, fig. 17A-17E are schematic cross-sectional views of stages of a process for attaching the light emitting cell 510 to the substrate 600, according to some embodiments of the present disclosure. The materials and processes of the intermediate structure up to fig. 17A may be similar to the embodiments described above with reference to fig. 16A-16D, and will not be repeated here.

In some embodiments, as shown in fig. 17B, the light emitting unit 510 and the expansion layer 530 are attached to the metal substrate 700. The metal substrate 700 may be copper, aluminum, molybdenum, tungsten, gold, chromium, nickel, platinum, titanium, iridium, rhodium, alloys thereof, or other metal materials with good electrical and thermal conductivity, or may be a shape memory alloy, such as: Ti-Ni, Cu-Zn, and Cu-Al-Ni.

Next, in some embodiments, as shown in fig. 17C, a heating process E is applied to the metal substrate 700. The metal substrate 700 expands due to heat, and thus the stretchable layer 530 is stretched by the expansion of the metal substrate 700. In some embodiments, the heating process E may be replaced by applying a current to the metal substrate 700.

Next, in some embodiments, as shown in fig. 17D, after the stretchable layer 530 is extended, the light emitting unit 510 is attached to the substrate 600. After the heating process E shown in fig. 17D, the distance between two adjacent light emitting cells 510 becomes D2 greater than D1.

Next, in some embodiments, as shown in fig. 17E, the metal substrate 700 is removed. In this embodiment, after the wafer 505 is removed, the pitch of each light emitting unit 510 is increased. Therefore, when the light emitting cells 510 are initially formed on the wafer 505, more light emitting cells 510 may be formed at a smaller pitch, without setting the pitch of the light emitting cells 510 to a desired pitch when the light emitting cells 510 are initially formed. Therefore, more light emitting cells 510 can be formed on a unit area of the wafer 505.

In addition, although fig. 17D-17E illustrate that the metal substrate 700 is removed after the light emitting unit 510 is attached to the substrate 600, the invention is not limited thereto. In other embodiments, the metal substrate 700 is removed, and then the light emitting unit 510 is attached to the substrate 600.

In addition, although fig. 17B-17D illustrate that the semiconductor layer of the light emitting unit 510 is attached to the metal substrate 700, the invention is not limited thereto. In another embodiment, the metal substrate 700 is attached to the surface side of the conductive pad of the light emitting unit 510.

Additionally, in some embodiments, wafer 505 is not a planar structure, but rather has a curved shape (not shown). In some embodiments, the appearance of wafer 505, as viewed in cross-section, may be v, ω, Ω, v, σ, or o. The curved surface has a local region of highest points, such as a ridge point or apex, and a local region of lowest points, such as a saddle point or a valley point.

Although embodiments of the present disclosure and their advantages have been disclosed above, it should be understood that various changes, substitutions and alterations can be made herein by those skilled in the art without departing from the spirit and scope of the disclosure. Moreover, the scope of the present disclosure is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification, but rather, the present disclosure may be readily understood by those of ordinary skill in the art from the disclosure of the embodiments of the present disclosure, and any variations, modifications, variations, or alterations that may occur to one skilled in the art may be made without departing from the spirit and scope of the present disclosure. Accordingly, the scope of the present disclosure includes the processes, machines, manufacture, compositions of matter, means, methods, and steps described above. In addition, each claim constitutes a separate embodiment, and the scope of protection of the present disclosure also includes combinations of the respective claims and embodiments.

Claims

1. A display device, comprising:

a light emitting unit, comprising:

a light emitting portion, wherein a first surface of the light emitting portion has a light extracting structure;

a connecting portion including at least one conductive pad and a bonding layer disposed on the conductive pad, the connecting portion being disposed on a second surface of the light emitting portion, wherein the second surface is opposite to the first surface; and

a protection part surrounding the light emitting part and the connection part; and

a substrate having a plurality of active components and at least one corresponding bonding pad, wherein the bonding pad is electrically connected to the connecting portion of the corresponding light-emitting unit;

wherein the roughness of the light extracting structure is greater than or equal to 0.2 μm, the bonding layer is electrically connected to the bonding pad of the substrate, and the light emitting unit is formed on a wafer before the light emitting unit is connected to the bonding pad of the substrate via the bonding layer, and the process of connecting the bonding layer to the bonding pad of the substrate includes:

coating a flexible layer on the wafer;

extending the telescopic layer; and

the light emitting unit is removed from the wafer.

2. The display device of claim 1, wherein each conductive pad is independently spaced apart from one another and adjacent to the second surface of the light emitting portion, the bonding layer has a first surface adjacent to the conductive pad and a second surface adjacent to the bonding pad, wherein the bonding layer has a first material layer and a second material layer, and wherein the first material layer comprises a first composition that is an alloy and the second material layer comprises a second composition that is a metal or alloy non-uniformly dispersed within the bonding layer.

3. The display device of claim 2, wherein the second composition comprises gold, silver, copper, nickel, platinum, tin, or alloys thereof; and the first component comprises tin-indium alloy, tin-zinc alloy, tin-silver alloy, gold-indium alloy and gold-tin alloy.

4. The display device of claim 3, wherein the bonding layer has a melting point of 100 ℃ or greater.

5. The display device of claim 2, wherein a concentration of the second component decreases in a direction from the first surface toward the second surface of the bonding layer.

6. The display device of claim 2, wherein the second component has a first concentration at the first surface of the bonding layer, a second concentration at the second surface of the bonding layer, and a third concentration between the first surface and the second surface, and wherein the third concentration is less than the first concentration and less than the second concentration.

7. The display device of claim 1, wherein the process of connecting the bonding layer to the bonding pads of the substrate further comprises:

before coating the telescopic layer on the wafer, a reflecting layer is formed on the wafer.

8. The display device of claim 1, wherein the process of connecting the bonding layer to the bonding pads of the substrate further comprises:

after the light-emitting unit is removed from the wafer, the light-emitting unit and the telescopic layer are attached to a metal substrate;

heating the metal substrate to expand the metal substrate and extend the stretchable layer; and

the metal substrate is removed.

9. A display device, comprising:

a light emitting unit, comprising:

the light-emitting part is provided with a first surface and a second surface arranged opposite to the first surface;

a connecting portion including at least one conductive pad and a bonding layer disposed on the conductive pad, and adjacent to the second surface of the light emitting portion;

a transparent structure disposed on the first surface of the light-emitting part; and

a substrate having a plurality of active elements and at least one corresponding bonding pad, wherein the bonding pad is electrically connected to the connecting portion of the corresponding light-emitting unit, wherein the refractive index of the transparent structure decreases in a direction from the second surface of the light-emitting portion toward the first surface of the light-emitting portion, the bonding layer is electrically connected to the bonding pad of the substrate, and the light-emitting unit is formed on a wafer before being connected to the bonding pad of the substrate via the bonding layer, and the process of connecting the bonding layer to the bonding pad of the substrate comprises:

coating a flexible layer on the wafer;

extending the telescopic layer; and

the light emitting unit is removed from the wafer.

10. A display device as claimed in claim 9, characterized in that the refractive index of the transparent structure is less than 2.4.

11. The display device of claim 9, wherein the transparent structure comprises:

a first transparent layer adjacent to the first surface of the light emitting part; and

and a second transparent layer disposed on the first transparent layer, wherein the light emitting portion has a refractive index greater than that of the first transparent layer, and the first transparent layer has a refractive index greater than that of the second transparent layer.

12. The display device according to claim 9, wherein the protective portion includes a highly reflective layer covering a part of the second surface of the light emitting portion.

13. The display device according to claim 9, wherein the transparent structure comprises an organic layer having a plurality of pores therein, wherein a distribution density of the pores is increased in the direction from the second surface toward the first surface of the light emitting portion.

14. The display device according to claim 9, wherein the transparent structure comprises an organic layer having a plurality of nanoparticles therein, wherein a distribution density of the nanoparticles decreases in the direction from the second surface toward the first surface of the light emitting portion.

15. The display apparatus of claim 9, wherein the conductive pad is adjacent to the second surface of the light emitting portion,

the bonding layer has a first surface adjacent to the conductive pad, an

And a bonding layer adjacent to a second surface of the bonding pad, wherein the bonding layer has a first material layer and a second material layer, and wherein the first material layer further comprises a first component that is an alloy, the second material layer further comprises a second component that is a metal or alloy non-uniformly dispersed within the bonding layer, wherein a concentration of the second component decreases in a direction from the first surface toward the second surface of the bonding layer.

16. The display apparatus of claim 9, the display apparatus having a blue pixel area, a green pixel area and a red pixel area, further comprising:

the first light-emitting unit is arranged in the blue pixel area, wherein the light emitted by the first light-emitting unit has a first dominant wavelength, and the light emitted by the first light-emitting unit is blue light;

a second light-emitting unit disposed in the green pixel region, wherein light emitted from the second light-emitting unit has a second dominant wavelength; and

a third light emitting unit disposed in the red pixel region, wherein light emitted from the third light emitting unit has a third dominant wavelength;

wherein a difference between the second dominant wavelength and the third dominant wavelength is greater than 4 nm.

17. The display apparatus of claim 16, wherein the first dominant wavelength is between the second dominant wavelength and the third dominant wavelength, and the third dominant wavelength is greater than the second dominant wavelength.

18. The display apparatus of claim 16 wherein the difference between the second dominant wavelength and the third dominant wavelength is greater than 10 nm.